more of a time distribution question
I've got a bunch (a pack?) of beaglebones that are connected via
ethernet (wired) and I want them to be (roughly) synchronized.
Running NTP (in some flavor) would be the obvious approach, but I'm in
an environment where there's no "outside" connectivity.. Could I make
one of the beaglebones be the NTP server, and the others be the clients?
(I've seen some "add a GPS to a Rpi to make a NTP server" projects, and
I could probably leverage that)
I've also got a laptop (a mac, as it happens).. what's involved in
making that be a NTP server (e.g. the Mac might get its time from a
NTP server at some higher stratum, and then it propagates it down).
Pointers to documentation would be appreciated.
On Thu, 30 Mar 2017 09:37:50 -0700
jimlux jimlux@earthlink.net wrote:
Running NTP (in some flavor) would be the obvious approach, but I'm in
an environment where there's no "outside" connectivity.. Could I make
one of the beaglebones be the NTP server, and the others be the clients?
Yes, you can tell ntpd to use the system clock as reference.
I have in my ntpd.conf:
---schnipp---
use hw clock in case no servers available
server 127.127.1.0 # local clock
fudge 127.127.1.0 stratum 10
---schnapp---
That makes the system clock a valid source. The fudge line is there
to prevent ntpd from using the local system clock as reference unless
it's the only source available.
Attila Kinali
--
You know, the very powerful and the very stupid have one thing in common.
They don't alters their views to fit the facts, they alter the facts to
fit the views, which can be uncomfortable if you happen to be one of the
facts that needs altering. -- The Doctor
On Thu, Mar 30, 2017 at 09:37:50AM -0700, jimlux wrote:
Running NTP (in some flavor) would be the obvious approach, but I'm in an
environment where there's no "outside" connectivity.. Could I make one of
the beaglebones be the NTP server, and the others be the clients?
Disciplining them all to a specific free-running host would
require the use of the LOCAL reference clock:
http://doc.ntp.org/4.1.2/driver1.htm
However, the LOCAL refclock is deprecated, and it is recommended
that you use orphan mode instead, which is its intended replacement:
https://www.eecis.udel.edu/~mills/ntp/html/orphan.html
http://support.ntp.org/bin/view/Support/OrphanMode
Orphan mode is designed for your use case, and allows for more
redundancy than making them all clients of a single host. I'd go that
route.
(I've seen some "add a GPS to a Rpi to make a NTP server" projects, and I
could probably leverage that)
You could do that, but you don't really have to -- you can keep
them synchronized at least to each other reasonably well this way.
I've also got a laptop (a mac, as it happens).. what's involved in making
that be a NTP server (e.g. the Mac might get its time from a NTP server at
some higher stratum, and then it propagates it down).
OSX already runs ntpd; you should just need to tweak their
default configuration.
--msa
https://www.eecis.udel.edu/~mills/ntp/html/orphan.html
On Thu, Mar 30, 2017 at 12:37 PM, jimlux jimlux@earthlink.net wrote:
Pointers to documentation would be appreciated.
On 3/30/17 1:11 PM, Majdi S. Abbas wrote:
On Thu, Mar 30, 2017 at 09:37:50AM -0700, jimlux wrote:
Running NTP (in some flavor) would be the obvious approach, but I'm in an
environment where there's no "outside" connectivity.. Could I make one of
the beaglebones be the NTP server, and the others be the clients?
Disciplining them all to a specific free-running host would
require the use of the LOCAL reference clock:
http://doc.ntp.org/4.1.2/driver1.htm
However, the LOCAL refclock is deprecated, and it is recommended
that you use orphan mode instead, which is its intended replacement:
https://www.eecis.udel.edu/~mills/ntp/html/orphan.html
http://support.ntp.org/bin/view/Support/OrphanMode
Orphan mode is designed for your use case, and allows for more
redundancy than making them all clients of a single host. I'd go that
route.
That's exactly what I was looking for. Didn't think about googling for
"orphan" (and really, this is a group of orphans)
(I've seen some "add a GPS to a Rpi to make a NTP server" projects, and I
could probably leverage that)
You could do that, but you don't really have to -- you can keep
them synchronized at least to each other reasonably well this way.
I've also got a laptop (a mac, as it happens).. what's involved in making
that be a NTP server (e.g. the Mac might get its time from a NTP server at
some higher stratum, and then it propagates it down).
OSX already runs ntpd; you should just need to tweak their
default configuration.
Yes, I got that figured out, although I need to figure out some network
routing issues now (independent of NTP...), since it was bridging (via
NAT) my pack of beagles to the outside world... I was going "from mac TO
beagle" with ssh, but I've got a problem going "from beagle to mac,
instead of big world"
But that's straightfoward to solve.
--msa
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